1. Field of the Invention
The present invention relates to thermal stimulation and recovery systems for subterranean wells.
2. Description of the Prior Art
Presently, low pressure, non-flowing oil wells account for the vast majority of the oil wells in the United States. There are various pump means available for pumping these non-flowing subterranean wells, the most common of these pump means being the sucker rod subsurface pump. Other types of pumps include electrical and hydraulic pumps. In a geothermal well, water can be pumped to a steam turbine in the bottom of the well where the water is turned into steam to drive the turbine.
Such non-flowing subterranean wells benefit from thermal stimulation. Energy can be transmitted to the bottom of the well in the form of steam or in the form of electricity to operate heating elements. The steam system has several disadvantages, some of which are air pollution caused by the fuel burning process in the steam boiler and the heating of the casing as the steam is transmitted through a conduit down the well. A major disadvantage of the electrical heating system is the difficulty in maintaining a selected heater temperature setting as the temperature of the surrounding area varies. A rapid increase in the temperature of the surrounding area would often cause the heater elements to overheat and burn up in the bottom of the well.